1/* vi: set sw=4 ts=4: */ 2/* mkswap.c - format swap device (Linux v1 only) 3 * 4 * Copyright 2006 Rob Landley <rob@landley.net> 5 * 6 * Licensed under GPL version 2, see file LICENSE in this tarball for details. 7 */ 8#include "libbb.h" 9 10#if ENABLE_SELINUX 11static void mkswap_selinux_setcontext(int fd, const char *path) 12{ 13 struct stat stbuf; 14 15 if (!is_selinux_enabled()) 16 return; 17 18 if (fstat(fd, &stbuf) < 0) 19 bb_perror_msg_and_die("fstat failed"); 20 if (S_ISREG(stbuf.st_mode)) { 21 security_context_t newcon; 22 security_context_t oldcon = NULL; 23 context_t context; 24 25 if (fgetfilecon(fd, &oldcon) < 0) { 26 if (errno != ENODATA) 27 goto error; 28 if (matchpathcon(path, stbuf.st_mode, &oldcon) < 0) 29 goto error; 30 } 31 context = context_new(oldcon); 32 if (!context || context_type_set(context, "swapfile_t")) 33 goto error; 34 newcon = context_str(context); 35 if (!newcon) 36 goto error; 37 /* fsetfilecon_raw is hidden */ 38 if (strcmp(oldcon, newcon) != 0 && fsetfilecon(fd, newcon) < 0) 39 goto error; 40 if (ENABLE_FEATURE_CLEAN_UP) { 41 context_free(context); 42 freecon(oldcon); 43 } 44 } 45 return; 46 error: 47 bb_perror_msg_and_die("SELinux relabeling failed"); 48} 49#else 50# define mkswap_selinux_setcontext(fd, path) ((void)0) 51#endif 52 53/* from Linux 2.6.23 */ 54/* 55 * Magic header for a swap area. ... Note that the first 56 * kilobyte is reserved for boot loader or disk label stuff. 57 */ 58struct swap_header_v1 { 59/* char bootbits[1024]; Space for disklabel etc. */ 60 uint32_t version; /* second kbyte, word 0 */ 61 uint32_t last_page; /* 1 */ 62 uint32_t nr_badpages; /* 2 */ 63 char sws_uuid[16]; /* 3,4,5,6 */ 64 char sws_volume[16]; /* 7,8,9,10 */ 65 uint32_t padding[117]; /* 11..127 */ 66 uint32_t badpages[1]; /* 128 */ 67 /* total 129 32-bit words in 2nd kilobyte */ 68} FIX_ALIASING; 69 70#define NWORDS 129 71#define hdr ((struct swap_header_v1*)bb_common_bufsiz1) 72 73struct BUG_sizes { 74 char swap_header_v1_wrong[sizeof(*hdr) != (NWORDS * 4) ? -1 : 1]; 75 char bufsiz1_is_too_small[COMMON_BUFSIZE < (NWORDS * 4) ? -1 : 1]; 76}; 77 78/* Stored without terminating NUL */ 79static const char SWAPSPACE2[sizeof("SWAPSPACE2")-1] ALIGN1 = "SWAPSPACE2"; 80 81int mkswap_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; 82int mkswap_main(int argc UNUSED_PARAM, char **argv) 83{ 84 int fd; 85 unsigned pagesize; 86 off_t len; 87 const char *label = ""; 88 89 opt_complementary = "-1"; /* at least one param */ 90 /* TODO: -p PAGESZ, -U UUID */ 91 getopt32(argv, "L:", &label); 92 argv += optind; 93 94 fd = xopen(argv[0], O_WRONLY); 95 96 /* Figure out how big the device is */ 97 len = get_volume_size_in_bytes(fd, argv[1], 1024, /*extend:*/ 1); 98 pagesize = getpagesize(); 99 len -= pagesize; 100 101 /* Announce our intentions */ 102 printf("Setting up swapspace version 1, size = %"OFF_FMT"u bytes\n", len); 103 mkswap_selinux_setcontext(fd, argv[0]); 104 105 /* hdr is zero-filled so far. Clear the first kbyte, or else 106 * mkswap-ing former FAT partition does NOT erase its signature. 107 * 108 * util-linux-ng 2.17.2 claims to erase it only if it does not see 109 * a partition table and is not run on whole disk. -f forces it. 110 */ 111 xwrite(fd, hdr, 1024); 112 113 /* Fill the header. */ 114 hdr->version = 1; 115 hdr->last_page = (uoff_t)len / pagesize; 116 117 if (ENABLE_FEATURE_MKSWAP_UUID) { 118 char uuid_string[37]; 119 generate_uuid((void*)hdr->sws_uuid); 120 printf("UUID=%s\n", unparse_uuid((uint8_t *)hdr->sws_uuid, uuid_string)); 121 } 122 safe_strncpy(hdr->sws_volume, label, 16); 123 124 /* Write the header. Sync to disk because some kernel versions check 125 * signature on disk (not in cache) during swapon. */ 126 xwrite(fd, hdr, NWORDS * 4); 127 xlseek(fd, pagesize - 10, SEEK_SET); 128 xwrite(fd, SWAPSPACE2, 10); 129 fsync(fd); 130 131 if (ENABLE_FEATURE_CLEAN_UP) 132 close(fd); 133 134 return 0; 135} 136